Recently, there has been growing interest in using silicon-based integrated circuits at high microwave and millimeter wave frequencies. This high level of integration offered by silicon enables numerous new topologies and architectures for low-cost reliable SoC applications at microwave and millimeter wave bands, such as broadband wireless access (e.g., WiMax), vehicular radars at 24 GHz and 77 GHz, short range communications at 24 GHz and 60 GHz, and ultra narrow pulse generation for UWB radar.
Power generation and amplification is one of the major challenges at millimeter wave frequencies. This is particularly critical in silicon integrated circuits due to the limited transistor gain, efficiency, and breakdown on the active side and lower quality factor of the passive components due to ohmic and substrate losses.
Efficient power combining is especially beneficial in silicon where a large number of smaller power sources and/or amplifiers can generate large output power levels reliably. Most of the traditional power combining methods use either resonant circuits and are narrowband or employ broadband, but lossy, resistive networks.
One-dimensional LC ladders have been extensively studied before. A homogeneous 1-D LC ladder consists of identical LC blocks repeated multiple times and can support wave propagation. It can also be used for broadband delay generation and low ripple filtering. An inhomogeneous linear 1-D line can be used to introduce controlled amounts of dispersion to a signal.